Planetary drum printer with movable gear segments to control type carrier rotation

ABSTRACT

Roller printer, especially for data processing machines, in which a rotatable drum has axial rods rotatable therein and circumferentially spaced near the periphery of the drum, each rod has a raised type element thereon to roll over a member to be printed thereon by rotation of the rod in a printing region. Each rod has an external gear segment thereon and an internal gear segment concentric with the drum is arranged to mesh with the external gear segments. A pawl is provided which is selectively operable to initiate rotation of the rods near the printing region to cause meshing of the external gear segments with the internal gear segment. The pawl is normally latched out of effective position by a latch lever arrangement and electromagnetic means connected to the latch lever arrangement is energizable for selectively moving the latch lever to release the pawl for movement into effective position.

United States Patent 1 Burkhardt et al.

[ Nov. 20, 1973 PLANETARY DRUM PRINTER WITH MOVABLE GEAR SEGMENTS TOCONTROL TYPE CARRIER ROTATION [75] Inventors: Gottfried Burkhardt,Winkelhaid;

Andreas Metschnabl, Numberg, both of Germany [73] Assignee: DIEI-IL,Nurnberg, Germany [22] Filed: Apr. 7, 1972 [21] Appl. No.: 241,913

[30] Foreign Application Priority Data Apr. 8, 1971 [52] US. Cl.101/110, 101/77 Germany P 21' 17 336.4

7/1964 Howard 101/110 X 7/1969 Huber lOl/llO X [5 7 ABSTRACT Rollerprinter, especially for data processing machines, in which a rotatabledrum has axial rods rotatable therein and circumferentially spaced nearthe periphery of the drum, each rod has a raised type element thereon toroll over a member to be printed thereon by rotation of the rod in aprinting region. Each rod has an external gear segment thereon and aninternal gear segment concentric with the drum is arranged to mesh withthe external gear segments. A pawl is provided which is selectivelyoperable to initiate rotation of the rods near the printing region tocause meshing of the external gear segments with the 12 Claims, 7Drawing Figures PATENTEU NOV 2 0 I973 SHEET 2 EF 3 PLANETARY DRUMPRINTER WITH MOVABLE GEAR SEGMENTS TO CONTROL TYPE CARRIER ROTATION Thepresent invention relates to a roller printer for data processingmachines with a continuously rotating type drum on which are rotatablyjoumaled toothequipped type elements which by a positive engagement witha control means roll on a printing station.

A printing principle of the above mentioned type has been disclosed inGerman patent No. 1,270,854, according to which the printing operationis carried out by combined rolling movements of a reversible pinion andof a type element cooperating therewith, said printing operation beingforced during the rotation of the drum. The roller movement of thereversible pinion is effected on a gear segment which is displaceableradially with regard to the drum and which is stationarily arranged inthe interior of the drum and is adapted to be actuated directly by anelectromagnet. The rolling movement of the type element occurs at theprinting station of the printing support. For returning the typeelement, there is provided a spring.

This printing principle will, in order to be able safely to control suchtype elements and reversing pinion, require a construction of arelatively large size, which is due to the meshing length of thedisplaceable gear segment. In connection therewith, with this controlmanner it is possible to obtain the high printing speed meeting modernrequirements only using relatively complicated constructions.

It is, therefore, an object of the present invention to provide asimpler and more compact roller printer with a type drum which will makeit possible with a high number of types, for instance, 45 types, toprint on an average 15 characters per second.

These and other objects and advantages of the invention will appear moreclearly from the following specification, in connection with theaccompanying drawings, in which:

FIG. 1 illustrates a typedrum for a series printer with a printingroller.

FIG. 2 is a partial section through an individual type element of FIG. 1with pawl.

FIG. 3 shows an electromagnet with scissors-shaped actuating mechanismfor the pawl of FIG. 2.

FIG. 4 shows the pawl of FIGS. 1 to 3 in operative position as seen fromabove.

FIG. 5 shows type elements with a dish section.

FIG. 6 illustrates a type drum with an alpha numerical printer.

FIG. 7 shows a portion of the printer of FIG. 1 with interengaging partsto facilitate understanding of the operation thereof.

The roller printer for data processing machines is characterized in thateach type element has associated therewith a gear segment which whencontrolling the type element by a pawl-shaped control means meshes withan inner gear segment that is associated with the printing area andrests relative to the type drum.

To this end the gear segment may be equipped with a guiding sectionformed by a missing tooth. This guiding section will directly after aneffected meshing of the gear segment with the inner gear segment abut aguiding surface which rests relative to the type elements, said guidingsurface arresting the type element in its starting position. I

The printing device according to the invention may advantageously becomposed of a few and simple elements in order positively to control allmovement sections, namely, the rolling of the printing type and thereturning of the type element. The type elements may thus be arrangedclosely adjacent in the type drum in view of the pawl requiring only aslight engaging width, so that the type drum may have only a smalldiameter.

According to a further embodiment of the present invention, the gearsegments of adjacent type elements having the shape of shafts may beaxially offset relative to each other so that adjacent gear segmentswill partially overlap each other in the type drum. As a result thereof,an even closer adjacent arrangement of the type elements and thus anextremely short drum diameter of low circumferential speed will be madepossible.

According to a further development of the invention, the tooth spaces ofthe inner gear segment are arranged in a dish extending around the typedrum, which dish by means of a guiding surface positively guides thetype elements through the intervention of their guiding section duringthe rotation of the type drum in its rest position. In this way, apositive guiding of the type element until the selection of the typeelement for roller printing, and a likewise positive return to itsstarting position will be made possible. I

For a series printer, according to a further development of theinvention, printing types may be arranged below an upper plate of thetype drum on the type shafts.

For an alpha-numerical printer with which each print is to be visibleimmediately, it is suggested according to a further feature of thepresent invention to provide printing types which are arranged on thetype shafts above an upper plate of the type drum. Between the typeshafts arranged in the type drum there are provided gaps so that aprinted type can without delay be recognized in view of astroboscope-like effect of the rotating type drum.

For controlling the type element, there may be employed, a pawl which iscontrollable by an electromagnet and which is provided with adouble-forked end face toward the type element. From said end, awedgeshaped pawl end is, for initiating the rolling of the type element,adapted to be moved or pivoted into the path of a control means in theform of a control tooth whereas the pawl is adapted by the other bluntpawl end to be returned by an abutment immediately after the pivotingmovement, said abutment being arranged on the type element and beingangularly offset relative to the control tooth. The wedge-shaped pawlend advantageously assures the timely engagement for selecting type tobe printed. A faulty type selection as it is possible with theheretofore known printer by belatedly controlling or controlling thereversing pinion or holding the latter for too long a time ispractically completely eliminated by the arrangement according to theinvention. The return of the pawl is brought about by the turningmovement of the type link. Therefore, no return spring is necessary incontrast to the heretofore known printer.

For assuring a safe operation, the printer according to the presentinvention is, according to a further development of the invention,equipped with an electromagnet which pivots a scissor-like element insuch a way that the pawl is pivoted by a spring into the path of thecontrol gear to be controlled in order subsequently to arrest the pawlin its starting position after it has been ejected or relieved by asecond scissor-shaped element. In this way, it will be assured thatalready an energization of the electromagnet will suffice to release thepawl which then independently of a possible timely delayed withdrawal ofthe armature is, by the second scissor-shaped element, secured in itsstarting position already prior to the starting position of the armaturebeing reached.

Referring now to the drawings in detail, according to FIGS. 1 and 2 atype drum 1 comprises an upper plate 2 and a lower plate 3 between whichat the circumference, type shafts 4 are rotatably joumaled. The typedrum 1 is connected to a shaft 6 which in a nonillustrated manner isjoumaled in the frame 5, for instance, of a writing carriage. Screwedonto the frame by means of supports 7' is a dish 7 which comprises thetype basket 1 within the range of gears 8 (FIG. 2) of the type shaft 4.Within the range of a printing roller 9, the dish 7 has an inner gearsegment 10 with five tooth spaces 11. Thus, the gear drive 8 has fiveteeth 12 l6 and a guiding section 17 formed by a missing tooth. On thetype shaft 4 shown by way of example in FIG. 2 there is provided anelevated type 18.

For frictional or positive holding of the type shaft in its startingposition there is provided a leaf spring 21 which is fastened to theupper plate 2 and engages a cam of the type shaft 4. A pawl 23 which bymeans of a pivot 22 is pivotally mounted in the frame 5 has that endthereof which faces the type shaft 4 provided with a double fork-shapedportion. Its upper wedgeshaped pawl end 24 cooperates with a controltooth 25 which is arranged on the type shaft 4, whereas the lower bluntpawl end 26 is adapted to be actuated by an abutment surface 27 of thetype shaft 4.

FIG. 3 shows the electromechanical operation of the pawl 23. An armature28 of an electromagnet 29 is, by means of a pivot 31, linked to a powerpivotable scissor-shaped element 30. The lower element 30 keeps by meansof a nose 32 a downwardly angled-off pawl end 33 in its rest positionagainst the thrust of a spring 34. An upper scissor-shaped element 35has its nose 36 spring biased by a spring 37 and rests on the back sideof the pawl 33. The angled-ofi' pawl end 33 is pivotable within therange of a recess 38 of the frame 5. A return spring 39 is provided forthe lower link 30.

FIG. 4 shows the working position of the pawl 23 which is controlled bythe energization of the electromagnet which pivotally controls the lowerlink 30. The angled-off link end 33 is pivotable in clockwise directionby the spring 34 and engages the upper end of the recess 38 of the frame5. The wedge-shaped pawl end 24 catches behind the control tooth 25.

According to FIG. 5, the gears 8', 8", 8" of adjacent type shafts 4",4", 4" are axially offset with regard to each other. Correspondingly,the guiding surface 40' of the dish 7' with the tooth spaces 11 has atleast double tooth thickness of the transmission 8 8".

FIG. 6 shows type shafts of which only two type shafts 42, 43 are shownin order to simplify the figure. These type shafts are rotatablyjoumaled in an upper plate 44 and in a lower plate 45 of a type drum 46.Printing types 47(A), 48 (F) are arranged on those ends of the typeshafts 42, 43 which protrude beyond the upper plate 44.

If a print of a type is to be made, the electromagnet '29 is actuated bya pulse of a commercially customary electronic control. The type drum 1will in these circumstances be in a continuously uniform rotation. Thepawl 23 is released by the scissor-shaped link 30 which is operable inthe direction of the arrow by the armature 28, and actuated by thethrust of spring 34 drops in front of the control tooth 25 of thetransmission to be selected. The wedge-shaped pawl end 24 will now inthe course of the further rotation of the type drum 1 turn the controltooth 25 as a result of which the type shaft 4 rotates about its axis,and the tooth 12 drops into the respective adjacent first tooth space11. The continuous rotation of the type drum 1 brings about the completerolling or development of the gear 8 in the inner gear segment 10 by anangle of 360 and thus the rolling or development of type 18 on a sheet,plate, or the like 41 on the printing roller 9. After the fifth tooth 16of the transmission 8 pivots out of the last one of the tooth spaces 11,tooth l2 abuts the guiding surface 40 of the dish 7. As a resultthereof, the type shaft 4 is again arrested in its starting positionaided by the leaf spring 21. The return of the pawl 23 is effectedshortly after the start of the rotation of type shaft 4. The blunt pawlend 26 is pushed back in counterclockwise direction by the abutmentsurface 27 of the type shaft 4. The upper scissor-shaped link 35 will bymeans of its nose 36, in case of the link 30 being returned too late,catch the angled-off pawl end 33 of pawl 23 in its starting position. Inthe course of the withdrawal of the lower link 30 by the electromagnet29, the upper link 35 frees the link 23 for engagement with the nose 32of the lower link 30. The starting position of the pawl as shown in FIG.3 is thus again restored.

In supplementing the above embodiment, it is also possible for dampingthe noise developed when selecting the respective type element forprinting purposes, advantageously slightly resiliently to journal theinner gear segment or the dish 7 relative to the frame 5. To this end,the dish 7 may be connected to frame 5 by means of suitably shapedrubber bodies.

As a record carrier there may be employed print sensitive paper. On theother band, also a colored band may be employed which is guided at theprinting place between the.printing types and the printing roller or acustomary paper band as record carrying means.

The operation of the device may best be understood from FIG. 7 in whichthe lever 30 engages the pawl lever portion 33 by means of nose 32 whenlever 30 is pivoted in the direction of the arrow A in response to theenergization of the electromagnetic means, nose 32 will release the pawllever 30 to the influence of its spring 34. When the pawl lever iscammed back by its cam end 26, if lever 30 has not yet returned, thelever 35 engages part 33 of the pawl lever 30 by nose 36.

Nose 36 is offset from nose 32, and when lever 30 returns, an abutmentelement B thereon pushes lever 35 back so that nose 36 leaves portion 33of the pawl lever 30 and releases portion 33 to drop against nose 32 oflever 30.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular constructions shown in the drawings,but also comprises any modifications within the scope of the appendedclaims.

What is claimed is:

1. In a roller printer, especially for a data processing machine; aframe, a rotatable drum in the frame, a printing region in the framedisposed in a predetermined circumferential position relative to theaxis of the drum, a plurality of rods extending axially of said drum andin circumferentially spaced relation near the periphery of the drum androtatable on the drum, each rod having a type element thereon operableto print on a member in said printing region and over which member thetype element is adapted to roll, an external gear segment on a firstperipheral portion of each rod, a second peripheral portion of each saidrod being free of any external gear segment, an internal gear segment inthe frame within the axial range of said external gear segments andwithin the circumferential range of said printing region and coaxialwith said drum but out of circumferential range of said secondperipheral portion of said rod, biasing means normally biasing saidexternal gear segments into such rotated position as to pass idly bysaid internal gear segment during rotation of said drum with the relatedrod in such rotated position that said type element remains out ofengagement with a member in said printing region, and control meansadjacent said printing region actuatable for causing a said externalgear segment to mesh with said internal gear segment as said drumrotates and carries the respective rod past said printing region therebyto cause the rod to rotate and roll the type element thereon on a memberin said printing region and print thereon.

2. A roller printer according to claim 1 in which each rod has a controlelement and in which said control means includes a pawl lever mounted insaid frame and moveable upon actuation into engagement with the controlelement pertaining to the external gear segment which is to mesh withsaid internal gear segment.

3. A roller printer according to claim 1 in which each external gearsegment is in the form of a gear with a missing tooth, an internalguiding surface coaxial with said drum, each external gear segment upondisengagement from said internal gear segment being in such rotatedposition that the teeth on opposite sides of said missing teeth engagesaid guiding surface and hold the respective rod against rotation insaid drum.

4. A roller printer according to claim 1 in which the said external gearsegments of adjacent ones of said rods are in axially ofiset overlappingrelation.

5. A roller printer according to claim 1 in which said internal gearsegment is formed in a ring coaxial with said drum and comprise apredetermined number of tooth spaces, each external segment comprisingthe same number of teeth as said number of tooth spaces and a gap formedby a missing tooth, the teeth of said external gear segment on oppositesides of said gap cooperating with the untoothed portion of the innerperiphery of said ring to hold the respective rod in a predeterminedposition on the drum as the drum rotates and carries the rod along saiduntoothed portion of the inner periphery of said ring.

6. A roller printer according to claim 1 in which said drum has axiallyspaced plates in which said rods are journalled, said type elementsbeing carried by said rods on the side of one of said plates oppositethe other said plate.

7. A roller printer according to claim 1 in which said drum has axiallyspaced plates in which said rods are joumaled, said type elements beingcarried by said rods between said plates.

8. A roller printer according to claim 2 in which said pawl lever ispivoted in said frame and has a first pawl end engageable with thecontrol element of a said rod upon actuation of the pawl lever wherebyrotation of said drum causes the respective rod to turn and bring theexternal gear segment pertaining thereto into mesh with said internalgear segment, said pawl lever having a second pawl end, and cam means onsaid rod engageable with said second pawl end when said rod rotates dueto engagement of the external gear segment thereon with said internalgear segment, said cam means being operable to move said pawl lever backto nonactuated position wherein said first pawl end is outside range ofsaid control elements.

9. A roller printer according to claim 8 in which said pawl lever isspring biased toward control element engaging position, a latch leverpivoted in said frame and having a nose engageable with said pawl leverwhen the pawl lever is in retracted position and spring urged towardpawl lever engaging position, and electromagnetic means connected tosaid latch lever energizable for withdrawing said latch lever fromengagement with said pawl lever.

10. A roller printer according to claim 9 which includes a second latchlever having a nose engageable with said pawl lever in the retractedposition of the pawl lever and operable to hold said pawl lever inretracted position prior to the first mentioned latch lever returning topawl lever engaging position following energization of saidelectromagnetic means.

11. A roller printer according to claim 10 in which the nose on thefirst mentioned said latch lever is offset from the nose on said secondlatch lever in the direction in which the region of said pawl leverengaged by said noses moves when the pawl lever is released to theinfluence of the biasing spring therefor, and means for disengaging saidsecond latch lever from said pawl lever when the first mentioned latchlever returns to pawl lever engaging position.

12. A roller printer according to claim 3 in which the control elementon each rod is in the form of a tooth axially spaced from the externalgear segment on the respective rod and circumferentially located on therod to align with the missing tooth on the respective rod.

' =0 II t i

1. In a roller printer, especially for a data processing machine; aframe, a rotatable drum in the frame, a printing region in the framedisposed in a predetermined circumferential position relative to theaxis of the drum, a plurality of rods extending axially of said drum andin circumferentially spaced relation near the periphery of the drum androtatable on the drum, each rod having a type element thereon operableto print on a member in said printing region and over which member thetype element is adapted to roll, an external gear segment on a firstperipheral portion of each rod, a second peripheral portion of each saidrod being free of any external gear segment, an internal gear segment inthe frame within the axial range of said external gear segments andwithin the circumferential range of said printing region and coaxialwith said drum but out of circumferential range of said secondperipheral portion of said rod, biasing means normally biasing saidexternal gear segments into such rotated position as to pass idly bysaid internal gear segment during rotation of said drum with the relatedrod in such rotated position that said type element remains out ofengagement with a member in said printing region, and control meansadjacent said printing region actuatable for causing a said externalgear segment to mesh with said internal gear segment as said drumrotates and carries the respective rod past said printing region therebyto cause the rod to rotate and roll the type element thereon on a memberin said printing region and print thereon.
 2. A roller printer accordingto claim 1 in which each rod has a control element and in which saidcontrol means includes a pawl lever mounted in said frame and moveableupon actuation into engagement with the control element pertaining tothe external gear segment which is to mesh with said internal gearsegment.
 3. A roller printer according to claim 1 in which each externalgear segment is in the form of a gear with a missing tooth, an internalguiding surface coaxial with said drum, each external gear segment upondisengagement from said internal gear segment being in such rotatedposition that the teeth on opposite sides of said missing teeth engagesaid guiding surface and hold the respective rod against rotation insaid drum.
 4. A roller printer according to claim 1 in which the saidexternal gear segments of adjacent ones of said rods are in axiallyoffset overlapping relation.
 5. A roller printer according to claim 1 inwhich said internal gear segment is formed in a ring coaxial with saiddrum and comprise a predetermined number of tooth spaces, each externalsegment comprising the same number of teeth as said number of toothspaces and a gap formed by a missing tooth, the teeth of said externalgear segment on opposite sides of said gap cooperating with theuntoothed portion of the inner periphery of said ring to hold therespective rod in a predetermined position on the drum as the drumrotates and carries the rod along said untoothed portion of the innerperiphery of said ring.
 6. A roller printer according to claim 1 inwhich said drum has axially spaced plates in which said rods arejournalled, said type elements being carried by said rods on the side ofone of said plates opposite the other said plate.
 7. A roller printeraccording to claim 1 in which said drum has axially spaced plates inwhich said rods are journaled, said type elements being carried by saidrods between said plates.
 8. A roller printer according to claim 2 inwhich said pawl lever is pivoted in said frame and has a first pawl endengageable with the control element of a said rod upon actuation of thepawl lever whereby rotation of said drum causes the respective rod toturn and bring the external gear segment pertaining thereto into meshwith said internal gear segment, said pawl lever having a second pawlend, and cam means on said rod engageable with said second pawl end whensaid rod rotates due to engagement of the external gear segment thereonwith said internal gear segment, said cam means being operable to movesaid pawl lever back to nonactuated position wherein said first pawl endis outside range of said control elements.
 9. A roller printer accordingto claim 8 in which said pawl lever is spring biased toward controlelement engaging position, a latch lever pivoted in said frame andhaving a nose engageable with said pawl lever when the pawl lever is inretracted position and spring urged toward pawl lever engaging position,and electromagnetic means connected to said latch lever energizable forwithdrawing said latch lever from engagement with said pawl lever.
 10. Aroller printer according to claim 9 which includes a Second latch leverhaving a nose engageable with said pawl lever in the retracted positionof the pawl lever and operable to hold said pawl lever in retractedposition prior to the first mentioned latch lever returning to pawllever engaging position following energization of said electromagneticmeans.
 11. A roller printer according to claim 10 in which the nose onthe first mentioned said latch lever is offset from the nose on saidsecond latch lever in the direction in which the region of said pawllever engaged by said noses moves when the pawl lever is released to theinfluence of the biasing spring therefor, and means for disengaging saidsecond latch lever from said pawl lever when the first mentioned latchlever returns to pawl lever engaging position.
 12. A roller printeraccording to claim 3 in which the control element on each rod is in theform of a tooth axially spaced from the external gear segment on therespective rod and circumferentially located on the rod to align withthe missing tooth on the respective rod.